The invention relates to an actuating means for a multispeed cycle hub having an axle defining an axis of rotation with two hub ends, a hub shell rotatably mounted on the axle, a transmission changeable among several speeds inside the shell, at least one drive gear in drive connection with an input element of the transmission, at least one output element of the transmission in drive connection with the shell, a bore extending along the axis of rotation in the axle and accommodating two elongated, compressionally rigid speed change elements extending parallel to the axis of rotation, the inner ends of the speed change element being coupled to the transmission for changing between speeds and outer end(s) of the speed change elements extending into the region of either of the two hub ends.
The actuating means is attached to one hub end. It is connected by way of a force-transmitting member to a speed selection means, which may be manually actuable, and which for this purpose is often arranged within reach of the cyclist. The force transmission member comprises for example a tensionally and compressionally rigid cable guided in a flexible sleeve extending between the actuating means and the speed selection means. To diminish the projection of the actuating means attached laterally to the cycle, i.e. the length of the actuating means parallel to the axis of rotation, the force-transmitting member is as a rule disposed in transverse direction to the axis away from the actuating means. By reason of the resulting deflection of force, the actuating means may be alternatively referred to as a deflecting means.
In the multispeed hubs here concerned (as a rule, more than three speeds, for example 5 or 7 speeds), however, the actuating means has still another function. For, in order to shift among the several speeds, in particular when a planetary gear is employed, the two speed-change elements initially referred to are required. One of the two speed-change elements serves for example to shift Between the steps of a multistep planetary gear. The other speed-change element, by contrast, permits shifting for example between a direct speed bypassing the planetary gear and grade speeds with power feed-in from the drive gear into the hollow gear of the planetary gearing, as well as high speeds with power feed-in from the drive gear to the planetary gear carrier of the planetary gearing. For actuation of these two speed-change elements independently of each other, two force-transmission members are required, which accordingly lead to two speed selection means or to a single combination speed selection means. These two force-transmitting elements, in conventional systems, are each passed out of one of the two hub ends. But this results in great structural as well as assembly and/or disassembly outlay.
The invention deals with an actuating means attached to one of the two hub ends, such that a single force-transmitting element will suffice. For this purpose, in the actuating means, both a shift motion for the one speed-change element and for the other speed-change element is derived from the linear motion of the one force-transmitting element between the various shift steps corresponding to the several speeds.
U.S. Pat. No. 4,947,703 (corresponding to European Patent 0,350,791 A2) discloses an actuating means of the kind initially mentioned in which an essentially U-shaped housing attached to one hub end accommodates two pivotably mounted sector shaped cams engaged directly by the force-transmitting member by way of a rigid U-shaped connecting part for actuation correspondingly. The two pivot levers are mounted by one of their two ends to a common hearing on the housing, while their other two ends each engage one of the two speed-change elements. Of the two speed-change elements, one is sleeve-shaped, while the other takes the form of a rod guided inside of the sleeve. The end of the corresponding pivot lever that engages the sleeve is therefore correspondingly fork shaped. Between their two ends, each of the two pivot levers is in contact with the corresponding cam, so that when the cams pivot because of a corresponding actuation of the speed selection means., they will push the speed-change element in question more or less far into the huh axle. The two cams together with their common pivot lie on the side of the pivot lever away from the cycle hub. The mechanics are not very robust, in particular owing to the use of small tubes and rods for the speed-change elements, with correspondingly complicated conformation of the ends of the two pivot levers, so that trouble is possible in rough everyday service.
U.S. patent application Ser. No. 08/063,930 (corresponding to European Patent Application EP 93 108 190.5) discloses a similar actuating means, in which, however, instead of the motion control of the pivot levers by way of two cams, there is a control by way of a linearly movable control part comprising two cams. Each cam is sensed by a sensor projection in the mid length region of the pivot lever in question. The control part is mounted directly on the end of the force-transmission member on the side of the pivot levers away from the cycle hub, to be thrust to and fro by the force-transmitting member to change speeds. Here also, the resulting structure is not very compact, with comparatively great axial length.